Why do my chickens lay down while eating?

They all do it sometimes, my baby silkies, my juvenile red sex links, and all my adults... Just randomly I'll look out in the back yard and some will be laying down but still eating. Are they just being lazy or could they have some sort of deficiency in their diet? The babies are in moveable 8'x8 pens so they have fresh grass to eat along with their non-medicated chick food, and the adults get let out to free range every day, and get fed layer pellets and corn also. And everyone gets black sunflower seeds.

Also how do I know if they are eating the sunflower seeds? The black hulls are everywhere, but for some reason I thought they would eat the whole thing, Or do they just eat the seed inside, which would explain why the hulls are still all over the place? The cardinals certainly wouldn't complain if the chickens never ate another seed again, every evening there are at least 6 cardinals in their pen... I love cardinals too though so I don't chase them off haha!

Why do people lay on the couch and eat? You could call it being lazy, or maybe they're tired- chickens will be chickens. My birdies don't eat the hulls, they just break them open and eat the seed inside. Good luck...

Yeah, it's usually okay. I often find the less energetic of the flock sitting somewhere in the shade picking grass from their immediate surrounds. Probably just resting.

As for the sunflower seeds, I don't imagine they'd eat the shell too. People don't either. We're often finding kernels of all sorts scattered around, that we didn't even notice was in the feed mix to begin with.